An electronic device with an ability of reproducing an audio signal including a CD player, an audio amplifier, a car stereo, a portable radio, or a portable audio player includes a sound processor for performing various signal processes on the audio signal. FIG. 1 is a block diagram showing a configuration of a typical audio system.
An audio system 1001 includes a sound source 1002, an analog amplifier 1004, an analog/digital converter 1010, a DSP (Digital Signal Processor or Digital Sound Processor) 1012, a digital/analog converter 1014, an analog amplifier 1006, a power amplifier 1008, and an electro-acoustic transducer 1009.
The sound source 1002 may be a CD player, a silicon audio player, a mobile phone terminal or the like that outputs an analog audio signal. The analog amplifier 1004 amplifies the analog audio signal from the sound source 1002 to match an input range of the subsequent analog/digital converter 1010. The DSP 1012 receives a digital audio signal from the preceding analog/digital converter 1010 to perform predetermined digital signal processes. The signal processes performed by the DSP 1012 may include equalizing, bass boost, treble boost, stereo/mono conversion, digital volume control, and so forth.
The digital/analog converter 1014 converts the digital audio signal processed by the DSP 1012 to an analog audio signal. The analog amplifier 1006, such as an analog volume circuit, amplifies the analog output signal of the digital/analog converter 1014 with a gain corresponding to a volume value. The power amplifier 1008 amplifies an output of the analog amplifier 1006 to drive the electro-acoustic transducer 1009 such as a speaker or a headphone.